全文获取类型
收费全文 | 72篇 |
免费 | 4篇 |
专业分类
化学 | 36篇 |
数学 | 1篇 |
物理学 | 39篇 |
出版年
2019年 | 2篇 |
2018年 | 1篇 |
2016年 | 3篇 |
2014年 | 1篇 |
2012年 | 2篇 |
2011年 | 10篇 |
2010年 | 1篇 |
2009年 | 2篇 |
2008年 | 4篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 1篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1973年 | 3篇 |
排序方式: 共有76条查询结果,搜索用时 31 毫秒
1.
Polycationic‐Shelled Capsular and Tubular Nanostructures and Their Anionic–Guest Binding Properties 下载免费PDF全文
Dr. Kohei Yazaki Dr. Yoshihisa Sei Prof. Dr. Munetaka Akita Dr. Michito Yoshizawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(49):17557-17561
For the development of novel nanospace with unique electrostatic character, we prepared new capsular and tubular nanostructures by the quantitative assembly of metal ions and bent bisacridinium ligands. The capsule and tube have closed spherical and open cylindrical cavities, respectively, with diameters of around 1 nm surrounded by cationic polyaromatic panels. Thanks to the facile synthetic protocol (three steps), another polycationic capsule with an elliptical nanocavity was also prepared by using an elongated ligand. In spite of the absence of pendant hydrophilic groups, the spherical polyaromatic capsule shows sufficient water solubility due to the polycationic shell. Moreover, the highly cationic cavity (12+) can selectively encapsulate anionic organic compounds in water. 相似文献
2.
Shuhei Uesugi Zhao Li Dr. Ryo Yazaki Prof. Dr. Takashi Ohshima 《Angewandte Chemie (International ed. in English)》2014,53(6):1611-1615
A highly chemoselective conjugate addition of alcohols in the presence of amines is described. The cooperative nature of the catalyst enabled chemoselective activation of alcohols over amines, allowing the conjugate addition to soft Lewis basic α,β‐unsaturated nitriles. Divergent transformation of the nitrile functionality highlights the utility of the present catalysis. 相似文献
3.
Alkylation‐, Heating‐, and Doping‐Induced Emission Enhancement of a Polyaromatic Tube in the Solid State 下载免费PDF全文
Kiyonori Kuroda Masafumi Otsuki Dr. Kohei Yazaki Dr. Yoshihisa Sei Prof. Dr. Munetaka Akita Dr. Michito Yoshizawa 《化学:亚洲杂志》2018,13(5):515-519
A polyaromatic tube with a subnanometer‐sized cavity was efficiently prepared on a gram‐scale through the stereo‐controlled cyclotrimerization of a diphenylanthracene derivative as a key step. The facile exterior alkylation of the polyaromatic framework leads to a moderately fluorescent tube (R=‐OC10H21; ΦF=20 %) in the solid state. The emission intensity of the solid‐state alkyl‐substituted tube is remarkably enhanced upon heating (up to 1.6 times, ΦF=31 %) as well as doping with fluorescent dyes (up to 4.2 times, ΦF=83 %) through efficient energy transfer. 相似文献
4.
Kohei Yazaki Shogo Noda Yuya Tanaka Yoshihisa Sei Munetaka Akita Michito Yoshizawa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(48):15255-15258
Preparation of molecular nanostructures with polyradical frameworks remains a significant challenge because of the limited synthetic accessibility which is entirely different from that of neutral and ionic ones. Herein we report the quantitative formation of a new M2L4 molecular capsule from metal ions and dihydrophenazine‐based ligands. The capsule has a spherical nanocavity (ca. 1 nm in diameter) enclosed by eight redox‐active, dihydrophenazine panels. Electrochemical oxidation of the capsule leads to the generation of multiple radical cations on the shell framework. Moreover, a stable tetra(radical cation) capsule can be reversibly obtained by chemical as well as electrochemical oxidation. 相似文献
5.
6.
The problem of pion condensation in isospin symmetric nuclear matter is investigated in the framework of the σ-model with a residual nucleon-nucleon interaction (g′σ1 · σ2τ1 · τ2δ(x)) and Δ-isobars. The equation of state for the pion condensed phase is calculated and applied to a low-energy heavy-ion collision in the TDHF approximation. The effective particle-hole interaction and the response to spin-isospin excitation are used to determine the magnitude of the Landau-Migdal parameter g′. For a reasonable range of g′(0.5 < g′ ≦ in units of g2/4m2N = 410 MeV · fm3) pion condensation occurs at densities above normal nuclear matter density and leads to an equation of state with no stable density isomer. 相似文献
7.
Annealing behaviors of the activation energy for electrical conduction, the optical gap, and the spin density in amorphous Si are investigated. It is found that the Fermi level shifts downwards with the decrease of the spin density, increasing the decay length of the wave function of localized state at the Fermi level. The downward shift of the Fermi level suggests that the localized states in the upper energy region in the gap are annealed out more easily than those in the lower one. 相似文献
8.
In this paper we present in a detailed and coherent fashion our work on QCD sum rules for equal mass heavy quark meson states. We discuss the technical procedures used to calculate the perturbative and non-perturbative contributions to the vacuum polarization, which have been calculated for all currents up to and including spin 2++. Using dispersion relations, sum rules are derived. Extensive applications are made to the lowest lying states of the charmonium and upsilon systems. The masses of the S- and P-wave charmonium levels are reproduced to a high degree of accuracy, and the mass of the 1P1 level is predicted at 3.51 GeV. For the upsilon system it only appears to be possible to predict the γ-ηb splitting which gives 60 MeV. Very accurate values are given for the current quark masses at p2 = ?mq2: mc = 1.28 GeV and mb = 4.25 GeV. 相似文献
9.
H. Sagawa N. Van Giai N. Takigawa M. Ishihara K. Yazaki 《Zeitschrift für Physik A Hadrons and Nuclei》1995,351(4):385-389
Decay of soft multipole excitations in halo nuclei is studied in comparison with the potential resonance state. Although the soft excitation has a sharp peak just above the particle threshold and carries extremely large transition strength, the decay rate looks much faster than that expected for a resonance state. Consequently, the half life is shown to be several orders of magnitude shorter than what one naively expects from the uncertainty principle. It is shown also that the soft excitations accumulate large transition strength as a non-resonant single-particle excitation, but not as particle-hole collective excitations like giant resonances. 相似文献
10.
Temperature dependence of the ESR signal intensity in amorphous SiGe films annealed at various temperatures is investigated. As a result, it is found that spins undergo a ferromagnetic interaction and the Curie-Weiss θ in the relation χ = C/ (T-θ) distributes between 40 and 135 K. The ferromagnetic behavior suggests that spins are inhomogeneously distributed and closely located together. 相似文献